Leaded/Unleaded

H8carbs H8carbs at aol.com
Fri Jan 2 17:21:02 GMT 1998


> a) On a GM vehicle, 2ltr 16V, ECU,  CAT, EGR, knock sensor etc.
>   Removing the CAT and running on Leaded fuel (higher octane rating).
>   Would ECU be able to tell ?, would any sensors (eg lamda) get 
> damaged ?

O2 sensor will probably get (lead dep) contaminated and set a code.
Buick racers often convert to the 3-wire (heated) sensors to combat
this problem.  The heated sensors hold up to leaded fuel much better
that the simpler one-wire units.  I have an AC/Delco unit right here.
There are two numbers on the box.  213-16 and 10096129..
It is a heated O2 sensor for GMC Syclone/Typhoon 4.3 liter V6.
 
The race fuels (Cam2, VP, etc) are heavily leaded, and a 
heated o2 sensor  can live for 3-9 months under those nasty 
conditions.  I think it's reasonable to assume that a heated
sensor would live much longer with 'lightly'(?)  leaded fuels.
Check your prestent sensor to see if it is 1 or 3 wire design.
If you switch from a single wire, to a 3 wire, contact me, and I'll
find out the exact wiring etc.

A more crude approach, which GMC used on Syclones 
that were shipped to SaudiArabia, would be to snip the 
sensor wire, and disable the O2 error flag in the ROM chip.
It was known as the  'NM8'  leaded gas chip,
Base inj pulse & spark tables were a litlle different too. 
Sorry so long winded.
Hope it helps
Mike V



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